scholarly journals Studies on Longer Wavelength Type II Radio Bursts Associated with Flares and CMEs during the Rise and Decay Phase of 23rd Solar Cycle

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
V. Vasanth ◽  
S. Umapathy
Keyword(s):  
Solar Cycle ◽  
Statistical Study ◽  
Decay Phase ◽  
Radio Bursts ◽  
Type Ii ◽  
23Rd Solar Cycle ◽  
Type Ii Radio Bursts ◽  
The Mean ◽  
Type Ii Bursts ◽  
Rise Phase

A statistical study on the properties of CMEs and flares associated with DH-type II bursts in the 23rd solar cycle during the period 1997–2008 is carried out. A sample of 229 events from our recent work is used for the present study (Vasanth and Umapathy, 2013). The collected events are divided into two groups as (i) solar cycle rise phase events and (ii) solar cycle decay phase events. The properties of CMEs in the two groups were compared and the results are presented. It is noted that there is no difference in the properties of type II burst like start frequency and end frequency between the solar cycle rise phase events and decay phase events. The mean CME speed of solar cycle decay phase events (1373 km s−1) is slightly higher than the solar cycle rise phase events (1058 km s−1). The mean CME acceleration of solar cycle decay phase events (−15.18 m s−2) is found to be higher than that of the solar cycle rise phase events (−1.32 m s−2). There exists good correlation between (i) CME speed and width and (ii) CME speed and acceleration for solar cycle decay phase events (R=0.79, R=-0.80) compared to solar cycle rise phase events (R=0.60, R=-0.57). These results indicate that the type II bursts parameters do not depend upon the time of appearance in the solar cycle.

scholarly journals On Split-Band Structure in Type II Radio Bursts from the Sun

1974 ◽  
Vol 57 ◽  
pp. 389-393 ◽  
Author(s):  
S. F. Smerd ◽  
K. V. Sheridan ◽  
R. T. Stewart
Keyword(s):  
Band Structure ◽  
The Sun ◽  
Radio Bursts ◽  
Type Ii ◽  
Band Splitting ◽  
Measured Amount ◽  
Type Ii Radio Bursts ◽  
Type Ii Bursts ◽  
Split Band

(Astrophys. Letters). The measured amount of band-splitting, Δf, in the spectra of nine harmonic type II bursts is illustrated in Figure 1. Here, as in previous, smaller samples (Roberts, 1959; Maxwell and Thompson, 1962; Weiss, 1965) Δf is found to increase with frequency, f.

On the Possibility of Radio Emission from Quasi-parallel and Quasi-perpendicular Propagation of Shocks

2000 ◽  
Vol 179 ◽  
pp. 259-262
Author(s):  
A. Shanmugaraju ◽  
S. Umapathy
Keyword(s):  
Magnetic Field ◽  
Radio Emission ◽  
Radio Bursts ◽  
Type Ii ◽  
Simple Analysis ◽  
Type Ii Radio Bursts ◽  
Solar Type ◽  
Type Ii Bursts

AbstractA set of 21 solar type II radio bursts observed using Hiraiso radio spectrograph have been analysed to study the direction of propagation of coronal shocks. A simple analysis is carried out to find the approximate angle between the shock normal and magnetic field by solving the Rankine-Hugoniot MHD relation with assumption of Alfven speed and plasma beta. From this analysis, it is suggested that both quasi-parallel shocks (favourable) and quasi-perpendicular shocks can generate type II bursts depending upon the circumstances of the corona.

scholarly journals Coronal mass ejections, type II radio bursts, and solar energetic particle events in the SOHO era

2008 ◽  
Vol 26 (10) ◽  
pp. 3033-3047 ◽  
Author(s):  
N. Gopalswamy ◽  
S. Yashiro ◽  
S. Akiyama ◽  
P. Mäkelä ◽  
H. Xie ◽  
...  
Keyword(s):  
Coronal Mass Ejections ◽  
Energetic Particle ◽  
Solar Energetic Particle ◽  
Western Hemisphere ◽  
Radio Bursts ◽  
Type Ii ◽  
Association Rate ◽  
Type Ii Radio Bursts ◽  
Type Ii Bursts ◽  
Weak Shocks

Abstract. Using the extensive and uniform data on coronal mass ejections (CMEs), solar energetic particle (SEP) events, and type II radio bursts during the SOHO era, we discuss how the CME properties such as speed, width and solar-source longitude decide whether CMEs are associated with type II radio bursts and SEP events. We discuss why some radio-quiet CMEs are associated with small SEP events while some radio-loud CMEs are not associated with SEP events. We conclude that either some fast and wide CMEs do not drive shocks or they drive weak shocks that do not produce significant levels of particle acceleration. We also infer that the Alfvén speed in the corona and near-Sun interplanetary medium ranges from <200 km/s to ~1600 km/s. Radio-quiet fast and wide CMEs are also poor SEP producers and the association rate of type II bursts and SEP events steadily increases with CME speed and width (i.e. energy). If we consider western hemispheric CMEs, the SEP association rate increases linearly from ~30% for 800 km/s CMEs to 100% for ≥1800 km/s. Essentially all type II bursts in the decametre-hectometric (DH) wavelength range are associated with SEP events once the source location on the Sun is taken into account. This is a significant result for space weather applications, because if a CME originating from the western hemisphere is accompanied by a DH type II burst, there is a high probability that it will produce an SEP event.

Relationship Between Rising Phase of Solar Cycle 23rd and 24th with Respect to Geoeffectiveness

2020 ◽  
Vol 12 (1) ◽  
pp. 70-74
Author(s):  
Beena Bhatt ◽  
Harish Chandra
Keyword(s):  
Solar Cycle ◽  
Solar Flare ◽  
Strong Correlation ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Cycles ◽  
Interplanetary Magnetic Fields ◽  
Type Ii Radio Bursts ◽  
Current Article ◽  
Mass Ejection

The current article demonstrates the geoeffectiveness of solar flare associated Coronal mass ejection (CME) accompanied with Deca-hectometric (DH) type II radio bursts by comparing the set of events in the rising phase of solar cycle 23rd (1996–2001) and 24th (2009–2014). Our observations are: (i) Solar cycle 23rd have high Dst index than the solar cycle 24th except for the year 1999. (ii) Dst has its peak between 3rd to 5th day after the CME onset for both the solar cycles. (iii) The correlation coefficient between Interplanetary magnetic fields (IMF) and Dst is good for both the solar cycles. (iv) Solar cycle 23rd have very strong correlation between CRI and Dst as compare to solar cycle 24th. Thus, our predictions show that solar cycle 23rd is more geoeffective than solar cycle 24th.

scholarly journals On the Issue of the Origin of Type II Solar Radio Bursts

2021 ◽  
Vol 922 (1) ◽  
pp. 82
Author(s):  
Gennady Chernov ◽  
Valery Fomichev
Keyword(s):  
Shock Waves ◽  
Radio Emission ◽  
Solar Atmosphere ◽  
Solar Radio ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Radio Bursts ◽  
Type Ii Radio Bursts ◽  
Type Ii Bursts ◽  
The Relationship

Abstract Type II solar radio bursts are among the most powerful events in the solar radio emission in the meter wavelength range. It is generally accepted that the agents generating type II radio bursts are magnetohydrodynamic shock waves. But the relationship between the shock waves and the other manifestations of the large-scale disturbances in the solar atmosphere (coronal mass ejections, Morton waves, EUW waves) remains unclear. To clarify a problem, it is important to determine the conditions of generation of type II radio bursts. Here, the model of the radio source is based on the generation of radio emission within the front of the collisionless shock wave where the Buneman instability of plasma waves is developed. In the frame of this model, the Alfvén magnetic Mach number must exceed the critical value, and there is a strict restriction on the perpendicularity of the front. The model allows us to obtain the information about the parameters of the shock waves and the parameters of the medium by the parameters of type II bursts. The estimates, obtained in this paper for several events with the band splitting of the fundamental and harmonic emission bands of the type II bursts, confirm the necessary conditions of the model. In this case the registration of type II radio bursts is an indication of the propagation of shock waves in the solar atmosphere, and the absence of type II radio bursts is not an indication of the absence of shock waves. Such a situation should be taken into account when investigating the relationship between type II radio bursts and other manifestations of solar activity.

Solar and interplanetary parameters of CMEs with and without type II radio bursts

2012 ◽  
Vol 50 (4) ◽  
pp. 516-525 ◽  
Author(s):  
A. Mujiber Rahman ◽  
S. Umapathy ◽  
A. Shanmugaraju ◽  
Y.-J. Moon
Keyword(s):  
Radio Bursts ◽  
Type Ii ◽  
Type Ii Radio Bursts

scholarly journals Coronal electron density distributions estimated from CMEs, DH type II radio bursts, and polarized brightness measurements

2016 ◽  
Vol 121 (4) ◽  
pp. 2853-2865 ◽  
Author(s):  
Jae‐Ok Lee ◽  
Y.‐J. Moon ◽  
Jin‐Yi Lee ◽  
Kyoung‐Sun Lee ◽  
R.‐S. Kim
Keyword(s):  
Electron Density ◽  
Radio Bursts ◽  
Type Ii ◽  
Density Distributions ◽  
Type Ii Radio Bursts ◽  
Coronal Electron

Investigation of X-class Flare-Associated Coronal Mass Ejections with and without DH Type II Radio Bursts

Solar Physics ◽  
2015 ◽  
Vol 290 (11) ◽  
pp. 3365-3377 ◽  
Author(s):  
M. Bendict Lawrance ◽  
A. Shanmugaraju ◽  
Bojan Vršnak
Keyword(s):  
Coronal Mass Ejections ◽  
Radio Bursts ◽  
Type Ii ◽  
Type Ii Radio Bursts ◽  
Class Flare
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